doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com TIG Welding

I recently purchased a new tig welder which is far better than the old hi-freq attachment I had.Does anyone have any practical experience filling in pits.Over the years I have passed on several otherwise really nice shotguns, but had pitting from poor storage.Is there a common sense limit on pit depth that should not be welded up and then fired etc.
thanks Dave

I saw Oscar weld up .020 pits and even a split damascus barrel at the muzzle end. I would let working pressure be my guide. A big pit on the reciever, sure. A big pit on the chamber, best think long and careful on that. I am sure it would cover but????
bill

Dave,

I have been welding for more that 25 years and the biggest limit is the talent of the welder. Practice as much as you can and you will quickly discover the limit of welding pits. Some are just to dirty at the bottom and getting them clean is impractical. Some are in to thin an area and you will cause penetration to the inside. Get a pitted up barrel and weld everything on it. Also realize that just because the weld looks good does not mean that it it structurally sound. after you weld them file the weld down and see if there is any porosity under the surface. If there is the weld is no good. E-mail me if you need some advice or help. I'll be glad to tell you what I can.

Bill G.

Post deleted by Run With The Fox

All good stuff. If welding outside pits in the thin areas of the barrel think about turning a close fitting copper or brass plug to fit the bore. This will be a heatsink when welding the O-too-thin areas and keep you from melting the wall into a hole. Some cold hammering on the welds with the plug inside also cold forges the grain structure a bit and hardens/toughens the weld. This is usually not necessary in the thin areas since the pressures are low there. Just more confidence factor.

Post deleted by Run With The Fox

One benefit of using tig is visibility (smoke). SMAW is not a great solution for small welds. Pre-heat and post heat are however.

Ultrasonic cleaning can help clean out the pits quite a bit, but like welding a cracked aluminum casting, it is very difficult to get all of the inclusions out.

I've been thinking of setting up to do some micro welding. I think I would make a box, and fill it with N2 or an Ar mix and do all the prep work down in the box.

For me, it's definately a cosmetic procedure.

I did extensive pit welding and cosmetic repair on a Win. 1892 receiver and bolt. My welder is a Miller MaxStar 151 inverter machine. Generally speaking, an inverter will sustain an arc at very low current (Miller says 1-amp on my machine)which is necessary for eliminating the crater when the arc is terminated. I use a thumbwheel current control on the torch handle. It makes it fairly easy to strike the arc, fill the pit and dial it down till the arc goes out leaving a smooth, rounded, fill where the pit was with a minimum size HAZ. I found that bead blasting did an adequate job of cleaning out the pits in preparatiion for welding.

I'm strictly a self taught welder and found that pit welding was not difficult after getting over the initial nervousness. However, I was not welding on a relativley thin, highly stressed shotgun barrel. That's a whole nuther deal and I defer to the experts in such situations.

OB

Thanks for all the advice. I bought a Lincoln 225 Precision Tig with a foot pedal current control which goes from 5 amps and up.
Is bead blasting the best way of cleaning out the pits,or is there a better way.Several years ago I filled in pitting on a mauser bottom metal which was severely pitted above the wood line.Bead blasted it but still had contamination in some of the welds.This was with my old welder the new one may have better cleaning abilities.I'm not a welder but generally don't let fear and common sense stop me.

Dave,

I prefer small burrs on a dremel tool. They are easy to consentrate on just the ares you are trying to clean and leave no residue behind.

Bill G.